Pi 3B+ - Touchscreen not working

Discussion about this major DATV Project. See https://wiki.batc.org.uk/The_Portsdown_Transmitter
Post Reply
Nick
Posts: 121
Joined: Sat Oct 03, 2015 10:09 am

Pi 3B+ - Touchscreen not working

Post by Nick » Thu Apr 26, 2018 5:53 pm

I have just obtained the new pi 3B+, fitted a waveshare screen and installed the stretch software from https://github.com/BritishAmateurTelevi ... /portsdown

When the software had installed and the system restarted the screen display appeared but the touchscreen would not work.

Have I missed something in the software that needs configuring ?

If not is there any way I can test the screen for problems ?

Regards,

Nick - G4NKV

Nick
Posts: 121
Joined: Sat Oct 03, 2015 10:09 am

Re: Pi 3B+ - Touchscreen not working

Post by Nick » Thu Apr 26, 2018 10:02 pm

I have rebuilt the software and got the same results.

By using putty I can see what happens from logging in - using the touch screen produces no output in putty, so most likely the screen is faulty.

Attached is the output using putty - can anyone confirm that everything looks OK from what is displayed ?

Nick - G4NKV
Attachments
Touchscreen not working.jpg
Touchscreen not working.jpg (544.01 KiB) Viewed 4335 times

G8GKQ
Site Admin
Posts: 2798
Joined: Sun Mar 22, 2009 1:21 pm

Re: Pi 3B+ - Touchscreen not working

Post by G8GKQ » Fri Apr 27, 2018 5:43 pm

Hi Nick

That all looks normal. I think that the touch sensor circuitry has failed.

Dave

G8PEF
Posts: 176
Joined: Mon Oct 30, 2017 6:42 pm

Re: Pi 3B+ - Touchscreen not working

Post by G8PEF » Fri Apr 27, 2018 11:18 pm

G8GKQ wrote:
Fri Apr 27, 2018 5:43 pm
Hi Nick

That all looks normal. I think that the touch sensor circuitry has failed.

Dave
Shouldn't 'Event code 0' have a value of 0 if the screen isn't being touched? It seems to be 2198... Is something pinching the LH edge of the display? A bezel or mounting of some sort, perhaps. However, having said that, wouldn't that cause 'Event code 24' to be non-zero?

Nick
Posts: 121
Joined: Sat Oct 03, 2015 10:09 am

Re: Pi 3B+ - Touchscreen not working

Post by Nick » Sat Apr 28, 2018 10:54 am

Thanks for the replies. I assumed it would be the screen that had failed so have ordered another one. The screen was mounted on the pi and that is all - it is not mounted in a case.

With regards to the event codes, etc, I have no idea what they mean so that's why I added the image. This was the first time I have created an operating system for Pi on an SD card and was not sure if I had done it correctly.

My intention was just to see if the OS had installed correctly and worked OK. Whilst it was installing I did note and error or two being mentioned, but I don't know what they were as they scrolled off the screen too quickly.

The replacement screen should arrive next week. I will test again and post the results here.

Nick - G4NKV

Nick
Posts: 121
Joined: Sat Oct 03, 2015 10:09 am

Re: Pi 3B+ - Touchscreen not working

Post by Nick » Tue May 01, 2018 11:04 pm

New screen fitted and works OK.

As I have nothing to lose I am going to see if the old screen can be fixed by replacing the HR2046 touch controller chip, assuming that this has failed. Will get one with my next order to Farnell.

gordon
Posts: 27
Joined: Sun Jan 21, 2018 6:52 pm

Re: Pi 3B+ - Touchscreen not working

Post by gordon » Tue Jun 05, 2018 4:30 pm

Hi, I have a 3.5inch waveshare type A touchscreen that does not respond to being touched. I am loathe to throw it away. Has anyone had any success repairing one?

Gordon

Nick
Posts: 121
Joined: Sat Oct 03, 2015 10:09 am

Re: Pi 3B+ - Touchscreen not working

Post by Nick » Sun Jul 01, 2018 8:13 am

I replaced the HR2046 touch controller chip (easy job after building the Portsdown) but this did not cure the problem. I then split the PCB from the screen to inspect the ribbon cable - all look OK.

Does anyone have a circuit diagram for the Waveshare touch screen - 3.5" RPi LCD (A) Revision 4.0. If so I may be able to investigate further.

Nick - G4NKV

g0mjw
Posts: 2329
Joined: Sat Sep 20, 2014 9:15 am

Re: Pi 3B+ - Touchscreen not working

Post by g0mjw » Sun Jul 01, 2018 8:23 am

It is a resistive touch screen, so you can measure the resistance X and Y on the cable and see what happens when you press it. Perhaps the flat flex cable is cracked, or not connecting properly?

Mike

Post Reply

Return to “The Portsdown Digital ATV System”